1. Field of the Invention
The present invention relates to an apparatus and method for fabricating harnesses by performing predetermined processing including terminating electric wires and stripping an intermediate region thereof.
2. Description of the Prior Art
Some harnesses for automotive vehicles include an insulation removed in its intermediate region for connection of a branch line to the intermediate region.
In the past, the harnesses have been fabricated by a harness fabricating apparatus for only terminating the harnesses, and the fabricated harnesses have been bundled and fed to the next step of manually stripping the intermediate region of the insulation by using a wire stripper or the like to form intermediate stripped harnesses.
However, such a method including the manual intermediate stripping process has caused variations in stripping accuracy depending upon individual abilities and, accordingly, unstabilized harness qualities. Further, a wire conveying step has been required for conveying the plurality of harnesses fabricated into a bundled form by the harness fabricating apparatus to the next step, resulting in an increased number of process steps.
To solve the foregoing problems, it has been desired to automate a series of processes from the wire terminating process to the intermediate stripping process. The applicant of the present invention has proposed a fully automatic harness fabricating apparatus as disclosed in U.S. Pat. No. 5,282,311.
FIG. 18 is a schematic side view of the harness fabricating apparatus of the above-mentioned application. The harness fabricating apparatus 300 generally comprises a straightener 310, an intermediate stripping mechanism 320, a wire path length adjusting mechanism 330, a wire feed mechanism 340, a wire guide mechanism 350, and a terminating portion 360. Operation of the respective components is controlled by a controller not shown.
An electric wire i unwound from a stock reel not shown passes through the straightener 3 10 including a plurality of upper and lower rollers 3 11 for straighten the curled wire 1, and is then stripped of an insulation in a predetermined intermediate region by the intermediate stripping mechanism 320. The stripping by the intermediate stripping mechanism 320 is carried out by grasping the wire 1 with a clamp 321, cutting into the insulation of the wire i with the forward ends of cutters 322, moving the cutters 322 to a position shown in broken lines of FIG. 18, and compressing the insulation rearwardly.
The wire path length adjusting mechanism 330 located downstream of the intermediate stripping mechanism 320 includes three rollers 331, 332, 333 around which the wire 1 is wound into an inverted U-shaped configuration. The wire path length adjusting mechanism 330 adjusts the length of the wire path between the intermediate stripping mechanism 320 and the terminating portion 360 to be described later to a predetermined length by vertically moving the middle roller 332.
The wire feed mechanism 340 drives two feed rollers 341, 342 for rotation thereof to feed the wire of a predetermined length in the direction of the arrow P. The wire guide mechanism 350 is adapted to provide slack to the wire 1 for ease of processing in the terminating portion 360 downstream thereof while guiding the wire 1 by using rollers 351, 352. The terminating portion 360 includes a front clamp 361, a cutter mechanism 362, and a rear clamp 363 which are arranged in this order, and further includes terminal crimping mechanisms (not shown) formed on opposite sides of the cutter mechanism 362 in a plane perpendicular to the plane of the drawings. In the terminating portion 360, the cutter mechanism 362 cuts off the wire 1 to a predetermined length and strips the insulation at the cut-off end, and the terminal crimping mechanism crimps a terminal to the stripped end of the wire 1. A pair of draw rollers 364 are provided upstream of the front cramp 361 for movement toward and away from each other. After the terminal crimping in the terminating portion 360, the pair of draw rollers 364 rotate so as to hold the wire 1 therebetween to feed the wire i in the P direction to haul in the slack of the wire i in the wire guide mechanism 350.
In the harness fabricating apparatus as above constructed, a series of processes from the wire terminating process including cutting of the wire 1, end stripping and terminal crimping to the intermediate stripping process are automated, and the wire path length adjusting mechanism 330 suitably adjusts the wire path length. Thus, when the wire 1 is aligned with a work position of the intermediate stripping mechanism 320, the wire 1 is simultaneously positioned at a work position of the terminating portion 360. Positioning of the wire 1 in different work positions is permitted by the single wire feeding operation, thereby providing efficient fabrication of the harnesses.
In the harness fabricating apparatus 300, the wire path length adjusting mechanism 330 for varying the wiring path length between the intermediate stripping mechanism 320 and the terminating portion 360 is adapted such that the wire 1 is wound around the three rollers 331, 332, 333 into the inverted U-shaped configuration and the middle roller 332 is vertically moved. Although the straightener 310 straightens the curled wire 1, the rollers 331, 332, 333 in the wire path length adjusting mechanism 330 curl the wire 1 again because of their small diameters. This results in errors of the length measurement by the feed roller 341 downstream of the wire path length adjusting mechanism 330 and deterioration of other working accuracy. Further, the finished harnesses which are curled create a poor appearance.
An approach to increase the diameter of the rollers 331, 332, 333 necessitates a wider space in the direction of a wire arrangement line in accordance with the increased diameter and a large-scale driving device for vertically moving one large roller, resulting in increased costs.